Related Publications

Something for Everyone: The AMA Guides and the Central Nervous System

By Robert G. Rassp, Esq.

AMA’s Guides to the Evaluation of Permanent Impairment, Fifth Edition, Chapter 13 on the central and peripheral nervous system, is one of the most important chapters in the Guides for our purposes as workers’ compensation attorneys. In most of our workers’ compensation cases, if there is any evidence of sensory or motor deficits, regardless of the part of body injured (head, brain, back, neck, upper extremities, lower extremities), then you should make sure the physician considers the criteria in this AMA Guides Chapter 13 in addition to any other applicable AMA Guides chapter for the specific body part(s).

Chapter 13 of the AMA Guides has something for everyone. However, under current case law in California, the physician must provide a strict WPI rating as the first step in determining an accurate permanent disability rating (the judge decides the PD rating while the physician decides the WPI ratings). If the strict WPI rating is not accurate, then the physician may utilize any chapter table or method within the four corners of the AMA Guides to find the most accurate WPI ratings that reflect the effect of impairment on the injured worker’s ADL functioning and work functioning.

In California, Guzman III issues with respect to rebutting a permanent disability rating arise in this chapter all the time because it is written by authors different than those who wrote the orthopedic Chapters 15, 16 and 17. The basic rule is for any head injury case, use Chapter 13 first, but don’t forget about other Chapters that may apply in a case. Also assume that with any head or facial trauma, there may be also co-morbidity -- a cervical spine injury that would be rated separately under Chapter 15 of the Guides as a first step.

You cannot thoroughly learn Chapter 13 without going through each table individually and closely following the text. While WPI ratings throughout the AMA Guides refer to impairments based on anatomic loss, diagnosis based, or functional loss, WPI ratings under Chapter 13 of the Guides are based almost entirely on functional deficits.

In light of the California Administrative Director’s rules on the use of the AMA Guides in the 2005 Permanent Disability Rating Schedule (PDRS), you need to refer to AMA Guides Chapters 13, 14, and 18, respectively, for neuropathic pain syndromes, the psychiatric sequelae of same, and any pain related impairments that have a greater than expected effect on the person’s ADL functioning than the impairment rating that applies under the appropriate part of body or organ function chapter in the AMA Guides. You will see under AMA Guides Chapter 18 that if there is pain related impairments where the majority of which are caused by psychological factors, then you use AMA Guides Chapter 14. On the other hand, if the pain related impairments have a concordant, credible pathophysiological basis, then you use AMA Guides Chapter 18.

The Central Nervous System

Chapter 13 defines the “central nervous system” to include the brain and spinal cord. Remember, the spinal cord is separate and distinct from the lumbar, thoracic, and cervical “spine”, which refer to the bones, ligaments, discs, and other structures that surround and protect the spinal cord. Chapter13 requires following the instructions in the text very carefully, especially for a strict WPI rating.

The authors of AMA Guides got sneaky in this chapter. Tables 13-15 through Table 13-21 on pages 336-342 are identical to corticospinal DRE ratings in Table 15-6 on pages 396-397. Or maybe they got sneaky in Chapter 15 using ratings from Chapter 13?

What is particularly vexing about reading and understanding Chapter 13 of the Guides is that physicians read the text, tables, and figures scientifically. Attorneys read the text, tables, and figures like attorneys -- each word means something and is subject to interpretation.

The most comprehensive part of AMA Guides Chapter 13 involves injuries to the central nervous system. This part applies in head injury cases, such as post concussion syndromes, strokes, traumatic epilepsy, seizure disorders, or any other brain injury. The effect of some injuries to the central nervous system to a person’s ADLs can be devastating. AMA Guides, Chapter 13, Section 13.1a, page 306, which describes in detail the symptoms that can be caused by a nervous system disorder, is a laundry list of symptoms that you can see in all other chapters of the AMA Guides.

On page 306 of the AMA Guides, the authors state:

“A permanent neurologic impairment is any anatomic, physiological, or functional abnormality or loss that remains after MMI. If impairments involve several nervous system areas (e.g. the brain, spinal cord, and/or peripheral nerves), calculate separate WPI ratings for each area and combine them.”

This is not correct in California because the 2005 PDRS mandates that each part of body be rated from WPI to permanent disability and thereafter combined, because each part of body may have a separate and different DFEC adjustment factor.

The authors go one to state on page 306:

“Because brain dysfunction will likely affect many overlapping functions , identify the most severe cerebral impairment. The impairment rating is based on the most severe impairment.”

This quote becomes controversial in obtaining a strict rating. Section 13.1a covers the usual signs and symptoms of brain injuries resulting in generalized or focal symptoms. Generalized symptoms are not localized to any one part of the body, while focal symptoms are limited to a specific area of the body. The term “focal” also refers to brain damage in a specific, identifiable area of the brain, such as a hemorrhage or contusion, while “generalized” brain damage refers to the entire brain or multiple parts thereof, such as with some forms of dementia.

It appears from a reading of the text in AMA Guides, Chapter 13, that the tables, figures, and examples can be used for stand-alone medical conditions other than a global brain or spinal cord injury. For example, Table 13-4 on page 317 covers impairments due to sleep and arousal disorders, and Example 13-17, page 318, is an impairment rating using Table 13-4 for sleep apnea, which is a stand-alone diagnosis and is not a result of a head injury in this example. Example 13-19 on the same page covers an impairment rating using the same Table 13-4 for narcolepsy (which is a condition that can be caused by reading this guidebook for too long at one time).

Signs, Symptoms, Complaints, and Tests

There is a list of signs, symptoms, and complaints associated with a brain injury or other disease or damage to the central nervous system from page 306 of the AMA Guides:

-Symptoms of brain injuries include:

--Alterations in levels of consciousness

--Memory loss, difficulty with language

--Headache, fatigue, weakness of limb or limbs

--Difficulty walking, loss of coordination

--Loss of bladder/bowel control

--Shooting pain, numbness, tingling in an extremity

--Sexual dysfunction

--Blurred or double vision

This list is not all inclusive because every brain injury is different and presents a variety of symptoms, changes in behavior, altered personality, altered moods, and cognitive deficits, such as difficulties with concentration, memory, and judgment. The authors state:

“Many of these symptoms describe the functional impairment experienced by the individual. The neurologic evaluation and ancillary clinical testing determine the origin of these symptoms.”

The authors go on to state at Page 306 a very important point without saying why the point is important:

“When this information is subjective and open to misinterpretation, it should not serve as the sole criterion upon which decisions about impairment are made. Rather, obtain objective data about the severity of the findings and the limitations and integrate those findings with the subjective data to estimate the degree of permanent impairment.”

This instruction is important because so many of the effects of a brain injury are subjective and impossible to objectively test. A closed head injury, one without a skull fracture, can have devastating effects on a person without any significant objective medical findings. So the physician must use what diagnostic tools that are available to him or her and try to objectify the cause of the symptoms, if possible, by some organicity. If there is no organicity, the physician must use his or her clinical judgment and experience to determine what he or she sees is from a brain injury.

Then the authors indicate the type of testing that should occur to determine the existence of a brain injury and the effects of it on the patient. Section 13.1b sets forth required clinical studies, including the neurological exam that identifies, if possible, the location of nervous system impairment. Ancillary testing (anatomic or physiologic) identifies the severity and location of the lesion and confirms underlying pathology. You cannot rate based on test results alone because the brain can compensate and ADLs may not be affected.

Neuropsychological assessment for cognitive and behavioral alterations should be conducted for the non-organic manifestations of brain injuries. These neuropsychological studies cannot be relied on alone to draw any conclusions about the cause of changes in behavior or psychiatric status. The authors tell us that neuropsychological evaluations must be performed in all brain injury cases, if possible, but the results must be interpreted with clinical findings and test results together. Neuropsychological test results do not form the basis of a diagnosis (e.g., dementia and Traumatic Brain Injury (TBI) may have the same findings on tests) and cannot determine the cause of a problem.

What is interesting about the central nervous system chapter is that the authors advocate use of tests we find in other chapters of the AMA Guides. Lumbar puncture (spinal tap, not a 1980s rock group) is recommended for a diagnosis of Multiple Sclerosis (MS), infections, and some peripheral nerve diseases. Evoked potentials for MS, optical neuritis, and neurotoxin exposures are recommended. Carotid duplex/Doppler flow for stenosis in carotid artery and for any kind of cerebro-vascular disease is recommended. CT scanning, including CT myelograms, is also recommended, presumably for confirmation of damage to the spinal cord.

The following tests are also recommended for organic diagnosis for either brain damage or spinal cord involvement: MRI or MRA (MR angiogram); PET Scans – mostly research in 2000, now used to show brain function, can show Parkinson’s disease; and SPECT testing, which shows changes in blood flow and metabolism that may account for abnormalities from dementia and neurodegenerative diseases. In addition, EMG (electromyelography) and nerve conduction velocity studies are necessary for determination of any peripheral nervous system disorders.

For detailed discussion of the step-by-step analysis of a person’s central nervous system impairment, see The Lawyer’s Guide to the AMA Guides and California Workers’ Compensation, 2012 Edition, Ch. 3, § 3.13.